Rear Window Defogger Function Test
NOTE:
  • Be careful not to scratch or damage the defogger wires with the tester probe.
  • Before testing, check the No. 12 (30 A) fuse in the under-hood fuse/relay box and No. 36 (10 A) fuse in the under-dash fuse/relay box.
  1. Check for voltage between the positive terminal (A) and body ground with the ignition switch ON (II) and defogger switch ON.
    There should be battery voltage.
    • If there is no voltage, check for:
      • -
      Faulty under-hood fuse/relay box.
      -
      Faulty rear window defogger/power mirror defogger switch.
      -
      An open in the wire between the under-hood fuse/relay box and the positive terminal.
    • If there is voltage, go to Step 2 .
  1. Turn the ignition switch OFF, and disconnect the negative terminal (B) from the rear window defogger.
  1. Check for continuity between the negative terminal (B) and body ground.
    • If there is no continuity, check for an open in the wire or poor ground (G701).
    • If there is continuity, go to Step 4 .
  1. Reconnect the negative terminal to the rear window defogger.
  1. Turn the ignition switch ON (II) and the rear window defogger/power mirror defogger switch ON.
  1. Touch the voltmeter positive probe to the each points on each defogger wire, and the negative probe to the negative terminal.
    • If the voltage is as specified, the defogger wire up to that point is OK.
    • If the voltage is not as specified, repair the defogger wire.
      • -
      If it is more than specified at one of the points, there is a break in the negative half of the wire.
      -
      If it is less than specified at one of the points, there is a break in the positive half of the wire.